Perfluorinated polyether compounds are compounds widely used as a lubricating oil, a coating agent, etc. Among such compounds, a derivative of which the terminal group is —CH2OH is known to be particularly useful. For example, a compound represented by the following formula (A) (in the formula (A), each of a and b represents an integer of at least 1) has been known (e.g. JP-A-6-44557 (page 2), C. Tonelli et al, J. Fluorine Chem., vol. 95, 1999, pages 51 to 70):HOCH2CF2O—(CF2CF2O)a.(CF2O)b—CF2CH2OH  Formula (A)
However, the compound represented by the formula (A) has —OCF2O— units derived from —(CF2O)— units as an essential component in its molecular structure, and thus it undergoes decomposition due to the above units, which may cause deterioration (e.g. W. Fong et al, IEEE Transactions on Magnetics, vol. 35, No. 2, March 1999, pages 911 to 912, J. Scheirs, Modern Fluoropolymers, John Wiley & Sons Ltd., 1997, pages 466 to 468, P. H. Kasai, Macromolecules, vol. 25, 1992, page 6791).
As a compound having no —OCF2O— units, a compound wherein the terminal groups (—CH2OH) in the formula (A) are —COOH groups, has been known. However, the compound wherein the terminals are —COOH groups has such a drawback that when it is exposed under high temperature conditions, the polar terminal groups (—COOH) easily undergo decarbonylation and are lost, and thus such properties that the surface coating properties repair in short time (also called self-repair properties) decrease. Further, it has such a drawback that it may cause corrosion since the —COOH groups have high acidity.
Further, there is a literature which discloses a compound represented by the following formula (B) as a surface active agent (JP-A-9-111286 (page 1)). However, the literature does not disclose a compound represented by the formula (B) wherein q is 0. Further, specifically disclosed compounds are all known perfluoropolyether surface active agents, and they correspond to compounds wherein q is at least 1:R1—CF2(O—CFR2—CF2)e—(O—CF2)f—R3  Formula (B)wherein R1 represents F or a hydrophilic group, R2 represents F or CF3, R3 represents a hydrophilic group, each of e and f is an integer of from 0 to 1,000, and one of them may be 0, the oxyperfluoro groups in the brackets may not necessarily be arranged in this order, and may be randomly polymerized, or may be alternately polymerized so that the oxyperfluoro groups are alternately arranged.